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Fault weakening caused by smectite swelling

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Title: Fault weakening caused by smectite swelling
Authors: Kameda, Jun Browse this author
Uno, Masaoki Browse this author
Conin, Marianne Browse this author
Ujiie, Kohtaro Browse this author
Hamada, Yohei Browse this author
Kimura, Gaku Browse this author
Keywords: 2011 Tohoku-Oki earthquake
Fault strength
Smectite
Swelling
Issue Date: 2-Dec-2019
Publisher: Springer
Journal Title: Earth planets and space
Volume: 71
Issue: 1
Start Page: 131
Publisher DOI: 10.1186/s40623-019-1108-5
Abstract: The large slip along the shallow subduction interface during the 2011 Tohoku-Oki earthquake (M(w)9.0) caused a huge tsunami that struck the northeast coast of Honshu, Japan. The Integrated Ocean Drilling Program Expedition 343 JFAST program revealed that the fault zone is composed primarily of smectite. Our swelling experiments using the fault material demonstrated that the swelling pressure systematically increases with a decrease in sample porosity. Based on in situ porosity estimations in the IODP borehole, the swelling pressure of the fault is as high as 8 MPa, which is comparable to the effective normal stress at the drill site (similar to 7 MPa). This also suggests that the modified effective confining pressure of the fault is quite low or potentially zero, meaning that fault strength is governed mainly by cohesion rather than frictional strength. The fault may therefore be intrinsically weak, which could enhance the coseismic displacement toward the trench when earthquake slip propagates from depth.
Type: article
URI: http://hdl.handle.net/2115/79608
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

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